The present disclosure relates to a power supply control device configured to control the supply of power via a plurality of switches.
Power supply control devices configured to control the supply of power from a battery to a load are installed in vehicles (e.g., see Japanese Patent 5772776). The power supply control device disclosed in Japanese Patent 5772776 includes two N-channel FETs (Field Effect Transistors), and the drain of one of the FETs is connected to the drain of the other PET. The source of one of the FETs is connected to a positive electrode of the battery and a source of the other FET is connected to one end of the load. A negative electrode of the battery is connected to the other end of the load.
Parasitic diodes are connected between the drains and sources of the two FETs. In the two FETs, the cathode of the parasitic diode is connected to the drain, and the anode of the parasitic diode is connected to the source. Therefore, in the power supply control device disclosed in Japanese Patent 5772776, the cathode of the parasitic diode of one of the FETs is connected to the cathode of the parasitic diode of the other FET.
If the two FETs are switched on together, a current flows between the drains and the sources of the two FETs, and power is supplied to the load from the battery. If the two FETs are switched off together, no current flows between the drains and the sources of the two FETs. Furthermore, because the cathodes of the two parasitic diodes of the two FETs are connected to each other, if the two FETs are off together, no current flows via the two parasitic diodes.
Also, even if the positive electrode of the battery is connected to the other end of the load and the negative electrode of the battery is connected to the source of one of the FETs in a state in which the two FETs are off together, no current flows via the two parasitic diodes, and thus no power is supplied to the load.